1. Field of the Invention
The present invention relates to an image forming apparatus provided with a transfer roller arranged opposite to a photosensitive drum (image carrier) carrying a toner image. The image forming apparatus forms the transfer roller and a conveying part in the vicinity of this transfer roller into a unit as a transfer and feeding unit.
2. Related Art
Hitherto, an image forming apparatus has been known which is provided with a transfer roller disposed opposite to a photosensitive drum carrying a toner image and in which the transfer roller and a conveying part in the vicinity of this transfer roller are made into a unit as a transfer and feeding unit.
If the transfer roller can be selectively disposed between a position opposite to the photosensitive drum and another position away therefrom to perform jam troubleshooting in this type of image forming apparatus, positioning of the transfer roller with respect to the photosensitive drum is important. For example, an image forming apparatus is known, in which a portion for positioning a transfer and feeding unit is disposed in a drum housing disposed close to the photosensitive drum or in a main body frame constituting a main body rather than positioning of a transfer roller is performed in the transfer and feeding unit that tends to accumulate larger tolerances.
Also, if the transfer roller is brought close to or away from the photosensitive drum, the transfer roller needs to be continuously pressed by a spring urging a force thereto with respect to the center of the photosensitive drum. Accordingly, it is necessary to employ a guide groove or the like for positioning the transfer roller such that the spring is allowed to press the transfer roller after the transfer and feeding unit is attached. Moreover, it is preferable that a fulcrum of rotation of the transfer and feeding unit is disposed on a lower side of the transfer and feeding unit and an upper side of the transfer and feeding unit is open so that a user can perform jam troubleshooting and the like easily.